Hydraulic control and actuator mechanism



HYDRAULIC CONTROL AND ACTUATOR MECHANISM I E. J. SVENSON Oct. 3, 1939.

5 Sheets-Sheet 1 Original Filed Dec. 21, 1931 fiuenzzi' Z J guewaon)Erna;

Oct. 3, 1939. E. J. svENsoN HYDRAULIC CONTROL AND ACTUATOR MECHANISM 5Sheets-Sheet 2 Original Filed Dec. 21, 1931 EM M '0' h 5 all LI m w mNwm e w F RN REM MN 7 N g4 II fl Sm WWW av NM 3| Q wS Mum 4 fin I T @wmmm RN 11 9mm l WWW mum L M %\.M Mi m \w %h\ WWNI m QNNI llbl| WWW N 6AME. J. SVENSON unaware CONTROL AND ACTUATOR MECHANISM Oct. 3, 1939.

01 'ig,inal Filed Dec. 21, 1931 5 Sheets-Sheet 3 Flag 254 w mm m m 6 02% M 4 J J 7 f w w 1 5 1 v V 4 M m J 49 .7 Wm Y 5% U E m w 3 9 a J m. za r Wii m E g 5 flu w a 5 .J 6. u J wmw J 4 w x 8 k 4 w w in J M; J d Q8v m or z Oct. 3, 1939. E. J. SVENSON 2,174,850 4 HYDRAULIC CONTROL ANDACTUATOR MECHANISM Original Filed Dec. 21, 193; 5 Sheets-Sheet 5Patented Oct. 3, 1939 UNITED STATES PATENT OFFICE,-

HYDRAULIC CONTROL AND ACTUATOR MECHANISM Ernest J. Svenson, Rockford,Ill., assignor to John S. Barnes Corporation, Rockford, 111., acorporation of Delaware 37 Claims.

My invention relates generally to hydraulic control and actuatormechanisms, and the present application is a division of my copendingapplication Serial No. 582,192, filed December 21, 1931 now Patent No.2,078,697, April 2'7, 1937.

In said parent application a machine tool, more particularly, anautomatic lathe is described and claimed, and in said application Icalled attention to the demand for material working apparatus ormachines which are particularly adapted to efiectively employ therelativelytough, hard cutting alloys which have been developed in recentyears, such as tungsten carbide, et cetera. This machine was designedwith the view of presenltinjgt suflicient sturdiness or rigidity forrendering the same particularly adaptable to be equipped with suchcutting tools. The present invention contemplates hydraulic control andactuator mechanisms of improved practical construction which cooperateto render a hydraulic. actuator more efliciently operable, and in thissense the present invention is by no means limited in its application tomachine tools, but is adaptable ior use generally in hydraulic actuatorsystems.

It is an object of the present invention to provide improved control"mechanisms for use in bydraulic systems and to this end the inventioncontemplates the provision of a new and improved tapered valve structurein which the pressure of fluid controlled by the valve is uniformlydistributed. s

More specifically, the present invention contemplates a valvearrangement as set forth above in which a counter-fluid pressure may beused for preventing slippage of fluid along the periphery of said valve.

The present invention also contemplates the provision of a new andimproved plunger pump construction wherein a valve of the type set forthabove forms an important constituent element thereof.

It is also.an object of the present invention to provide for use in ahydraulic actuator system a unitary frame supporting structure forsupporting as aunit, a rotary supporting member or spindle, fluidpressure generating means or pump, and a fluid reservoir whereby fluidmay be maintained in association with said rotary supporting member fordissipating heat generated by the rotation of said. supporting member orspindle.

It is also an object of the present invention to provide a hydraulicactuator system in which. means is provided whereby at least twopressure conditions may be established by fluid which is delivered froma single source of supply, and to this end I propose to direct fluidfrom a suitable fluid pressure generating means, such as a low pressurepump, in such a manner as to establish two fluid pressure conditions.

The foregoing and numerous other objects and advantages will be moreapparent from the following detailed description when considered inconnection with the accompanying drawings, wherein- 'Figure l is an endelevational view of an automatic lathe in which the present invention isembodied;

Figure 2 is an enlarged vertical sectional view of the oil reservoirtaken substantially along the line 2-2 of Figure 13;

Figure 3 is an enlarged fragmentary elevational view disclosing themechanism for controlling the operation of the main control valve, saidcontrol valvebeing shown in central vertical section to more clearlyillustrate the structural characteristics thereof;

Figure 4 is a vertical sectional view of the main control valve andoperating mechanism therefor, said view being taken substantially alongthe line 4-4 of Figure 3:

Figure 5 is a central vertical sectional view of one of the highpressure plunger pumps disclosing my improved rotary valve construction;

Figure 6 is a transverse sectional view of the valve structure taken;substantially along the line 6-6 of Figure 5;

Figure '7' is a similar view taken along the line 1-1 of Figure 5;

Figure 8 is likewise a similar cross sectional view taken along the line8-8 of Figure 5;

Figure 9 is a transverse sectional view of the pump taken substantiallyalong the line 9-9 of Figure 5;

Figure 10 is an elevational view of a conventional self-expandingcompensator, which is representative of one type of compensator adaptedto be employed in combination with my improved rotary tapered valve;

Figure 11 is a detail transverse sectional view of the main controlvalve taken substantially along the line lI-l l of Figure 3;

Figure 12 is a transverse vertical sectional view of the valve forcontrolling the longitudinal movement of the front carriage, said viewbeing taken substantially along the line I2-l2 of Figure 4;

Figure 13 is a fragmentary front elevational view of the head stock andcarriage portions of the lathe to more clearly illustrate the hydrauliccontrol and actuator mechanisms of the present invention;

Figure 14 is a diagram disclosing the general arrangement of the fluidcircuits incorporated within my improved system of hydraulic control;

Figure 15 is an enlarged central sectional view of a pressure controldevice which. is coupled with the discharge side of the gear pump;

Figure 16 is a fragmentary plan-view taken substantially along the lineI8I8 of Figure 4;

and

Figure 1'7 is a plan view of the automatic lathe shown in Figures 1 and13.

In describing the present invention I have found it expedient todisclose certain portions of the lathe structure, but in view of thefact that the present invention is not directed to the lathe or machinetool structure per se, a detailed description and explanation thereofwill not be,

necessary for a clear understanding of the present invention. Therefore,I shall not enter into a detailed description of the machine structuresexcept as such structures may enter into combination with other elementsas contemplated by the present invention.

It will suffice to say that the machine tool or automatic lathedisclosed herein comprises a unitary casting 48 which is shown inFigures 1, '2 and 13. This-casting 48 includes a machine base or bed 42,and formed integral with the bed and surrounding same is a trough 44which serves to collect chips, cooling fluid, and the like. Extendingupwardly and formed integral with the base or bed "at one end thereof isa head stock section designated generally by the numeral 48. Thissection 48 is cast in one piece with the bed and provides a support fora rotary support-' ing member or spindle 58.

Particular attention is directed to the fact that this unitary headstock section or frame 48 is not only designed to support or carry thespindie 58, but is also designed to serve as a fluid reservoirdesignated generally by the numeral 52, see particularly Figure 2. Acover or frame member 54 carried by the unitary frame 48 supports a pairof plunger pumps 58 and 58.

The unitary frame or bed 42 also carries a suitable prime mover orelectric motor 88 which is connected, through the agency of a suitablechain 82, with a transmission mechanism including suitable clutchmechanism 88 (Figure 17) which serves to control the delivery of powerto the work supporting spindle 58 through suitable gearing shown inFigures 1 and 17. Mounted upon the bed 42 (Figure 1) is a gear pump 88which is continuously driven from the aforesaid transmission. This gearpump 88 is preferably of the type disclosed in my Patent No. 1,912,737and is adapted to supply fluid for rapid traverse purposes,'-while theplunger pumps 88 and 88 are;

preferably of the variable displacement type which are adapted todeliver fluid at a slower feeding rate. r

A front tool carriage is denoted generally by the numeral 88 (Figures 13and 14) and is mounted upon a horizontally and longitudinally shiftablebar 82. This bar is supported within the bed 42 and the rear toolcarriage denoted by the numeral 84 is reciprocably mounted on the rearupper surface of the bed 42, and is adapted to be reciprocatedtransversely of'the axis of the work supporting spindle 58.

The front carriage 88 is adapted to oscillate about the axis of theslidable bar 82, and moves as a unit longitudinally with the bar 82;Movethe free extremity of an oscillatory guide bar I84, which serves toguide a roller I85. This roller I85 is carried beneath the outer portionof the structure of the oscillatory carriage 88. It will sufllce to saythat the initial movement experienced by the front carriage 88 isoccasibned by the actuator 98, the upward movement of which causes thecarriage 88 to swing toward a work piece supported by the spindle 88. Atailstock 12 cooperates with the headstock 48 in supportin a work pieceto be acted upon by tools carried by the front and rear carriages 88 and84, respectively. Longitudinal movement is imparted to the frontcarriage 88 by a hydraulic actuator indicated generally by the numeral4,, which includes a cylinder H8 and a piston II8, said piston beingcoupled with the left extremity of the oscillatory and longitudinallyshiftable bar 82 by means of a piston rod I28. From the foregoing itwill be apparent that the hydraulic actuator 98 serves to movea tool onthe carriage 88 into cutting position with respect to a supported workpiece, and the hydraulic actuator II4 serves to impart movement to saidtool. lonmechanism I58I88 (Figure 1'1) to effect rota tion of ahorizontally disposed shaft I82.. This shaft I 82 extends longitudinallyof .the machine and is geared to a transverse shaft I84. The extremityof the shaft I84, which terminates at the front of the machine, carriesa gem-I88 (Figures land 3). Thus it will be understood-that, whenmovement is imparted to the rear tool carriage 84 toward the work piece,acldckwlse movement will be imparted to the gear I88; and acounter-clockwise movement to the com on gear I88, .as viewed in Figure3.

A rotary valve control mechanism I58 is designed to timingly control theshifting of a main .control valve mechanism designated generally by thenumeral I18, which is mounted on the front side of the machine in aconvenient posi-. tion to be manipulated by the operator. In order tosimplify an understanding of the structural and functionalcharacteristics of the main control valve I18 and the rotary controlmechanism I88 therefor, .1 shall describe these parts in connection withthe hydraulic system of control,

which governs the timed or synchronous movements of the various latheelements, such as the tool carriage and the fluid pumps. It will be seenthat the valve mechanism I18 includes a casing or housing I12, whichsupports a pair of reciprocable valve members I14 and I18, said valvemembers being coupled by means of a connecting element I18. It 'willalso be seen that the rotary control mechanism I58 includes a plate mprovided with a -r slot I82, which is adapted to adjustably receiveaplurality of dogs I84, I88, I88, I88, and I82. This plate I88 isrotatable with the gear I68 and is supported by a stub fast I94.

Assume that a cylindrical work piece is properly mounted between thespindle of the headstock 48 and the center of the tailstock 12, and thatthe front carriage 80 occupies its limited downward position, and thatthe rearcarriage occupies its rear position. Assume further that thevalve members I14 and I16 occupy the neutral position shown in Figure 3,and that the dogs on the rotary plate I also occupy the relativeposition shown in Figure 3.; The prime mover or electric motor 60 is nowoperating and causes the gear pump 68 to be activated. The clutchmechanism 66 is positioned so as to disconnect the work supportingspindle 50 from the prime mover, and thus the plunger pumps 56 and 58are not activated. The operator shifts a control handle I96 (Figure 17)to the left, and said handle, being connected with the valve members I14and I16 by an arm I98, causes said valve members to be shifted to theright, as viewed in Figure 3. In this shifted position fluid from thegear pump 68 is directed through a distributor mechanism 200 (Figures 14and 15), later to be described, and thence through a pipe line 202(Figures 3 and 11), which communicates with a passage 204 of the valveI14 and a passage 206 of the valve I16. The valve passage 204 is now incommunication with a pipe line 206, while the passage 206 is closed to apipe line 2I0, which connects with the valve mechanism. Fluid With inthe pipe line 208 passes into the lower end of the cylinder I00 of theactuator 96 (Figure 14), thereby causing the piston 98 to be shiftedupwardly. This results in the movement of the tool on the front carriagetoward the work piece' and in the passage of fluid from the cylinder I00through a pipe line or conduit 2I2, a check valve 2I4, and a conduit2I6' which is connected with a hydraulic actuator 2| 8, thelatterserving to control the clutch mechanism 66. Fluid thus introducedwithin the actuator 2I8 causes a piston 220 to be shifted to the left(Figure 14) within a cylinder 222, and thus establishes drivingconnection between the prime mover 60 and the work supporting spindle50. Fluid from the hydraulic actuator 2 I 8 passes through a conduit orpipe line 224 into the rear extremity of the cylinder I26 of the rearcarriage actuator I24. It will thus be apparent thatthe shifting of thevalve members I14 and I16 to the right (Figure 3) causes the frontcarriage 80 and the rear carriage 64 to be moved at a rapid rate intocutting position with respect to the work piece.

The advancement of the rear carriage causes the rotary dog support I80to be shifted in the counter-clockwise direction, as viewed in Figure 3.The dog I66 is eventually moved into engagement' with a finger 226carried at the lower end of a shaft 228, which supports the valvecontrol handle I96, and this causes the valve members I14 and I16 to bereturned to the neutral position shown in Figure-3. The plunger pumps 56and 58 which wer'e'automatically actuated upon the establishment ofdriving connection between the spindle 50 and the prime mover 60 nowserve to deliver fluid athigh pressure through pipe lines or conduits280 and 232, respectively (Figure 14). This causes the advancement oftherear tool carriage 64 at a feeding rate across the face of the workpiece and the longitudinal travel at a feeding rate of the front toolcarriage 60, the'tooi supported thereby cutting along the periphery ofthe work piece. Fluid from theadvancing side of the actuator piston I26is directed through a line or conduit 234 back to the plunger pump 56.and fluid from the advancing side of the actuator II8 passes through aconduit 23.6, a front carriage control valve 236, and a conduit 240 backIt will be to the intake side of the pump 56. observed that the dog I92,upon engaging a finger 242 carried by'a shaft 244 of the valve 238(Figure 3) causes said valve to establish communication between theconduits 236 and 240 at the desired interval so as to timingly controlthe longitudinal travel of the front carriage.

The feedingstroke of the hydraulic actuators H4 and I24 continues untilthe dog I86 is moved into engagement with the outer end of a valvemember 246 (Figure 3). Shifting this valve member to the left againstthe action of a coil spring 246 effects a sudden establishment ofcommunication between a valve chamber 252 and the fluid reservoir 52. Inother words, when the valve member 246 shifts to the left, communicationbetween a passage 254 and the chamber 252 is closed, and fluid from thechamber 252 flows unrestrictedly through a central valve passage 258, aradial port 260, and a pipe line or conduit 262.. The sudden release offluid from the chamber 252 enables the normal fluid pressure within anopposite valve chamber 264 to cause the valve memhers I 14 and I16 to besuddenly shifted to the left.

In this position said valve members initiate a flow of fluid in thereverse direction to the hydraulic actuators I24 and H4. Thus, in thisreverse position, fluid from the gear pump 68 passes through the valveports 204 and 206 into pipe lines 266 and 268, respectively, (Figures 3and 14).-

pipe line 266 is directed into the pipe line 236 and thence into theleft end of the actuator cylinder II6. It will thus be apparent that thefront tool carriage is moved at a rapid rate in a reverse direction,namely, to the right, and that the rear tool carriage is similarly movedinto a reverse direction. The dog I carried by the rotary support I80eventually engages a finger 210 oppositely disposed from the finger 242,thereby closing the valve 236, and the dog I 84 is eventually moved intoengagement with a finger 212 (Figure 4), so as to cause the valvemembers I 14 and I 16 to be again shifted to their neutral position.This completes the cycle of operation, which may be repeated by merelyshifting the control handle in the manner justdescribed.

It will be noted that, when the valve members I14 and I16 occupy theirneutral position, fluid from the rapid traverse or gearpump 68circulates through radial ports 214 and 216, respectively, whichcommunicate with central valve passages 218 and 280 (Figure 3). Thesecentral passages open into the valve chamber 264, which communicateswith the opposite valve chamber 250 through line for the hydraulicactuator 96 (Figure 14), thereby enabling the front carriage to suddenlyand automatically shift forwardly so as to bring the tool on the frontcarriage out of engagement with the work piece. 1 1.

. .a longitudinal connecting passage 262 (Figure'll) When the valvemembers "4 and "6 occupy their neutral position, as shown in Figure 3,they render the gear pump functionally inoperative for propellingpurposes, and provide an effective seal for the high pressure circuit.In other words, when the plunger pumps 56 and 58 function to propeltheir respective hydraulic actuators at a feeding rate, said pumps areconnected within closed circuits. the fluid on the discharge side-of theactuator piston being suflicient to charge the plunger pump. In fact,fluid from the advancing side of these actuator pistons provides thesole charging fluid for the plunger pumps.

Particular attention is directed to the structure of the plunger pumps56 and 53, and in this connection special reference is made to Figures 5and 10, inclusive. Both of the pumps 56 and 58 are identical inconstruction, and therefore a description of one will suflice for adescription of the other. Each of these pumps includes a central casing284, an end casing section 288 secured thereto by means of bolts 238,and an oppositely disposed end section or support 290. This support 290houses a plurality of radial reciprocable plungers or pistons 292, theinner ends of which engage the curved surfaces of pivoted fingers 294.These fingers, in turn, rest upon the peripheral surface of a drivingring 296 rotatably supported upon an eccentrically adjustable drivingmember 298. By displacing the center of the ring 296 from the center,about which the pistons 292 radiate,

and then rotating said ring, the pistons are successively urgedoutwardly to compress fluid in chambers 390. The eccentric adjustment ofthe driving member 299 is controlled by means of suitable adjustingmechanism, which includes a longitudinally shiftable member 332, whichis provided with a projection 304 extending into a companion recessprovided in the driving member 293. .This projection 304 is inclined.with respect to the axis of rotation, and when longitudinal movement isimparted to the member 332 in response to the turning of a cap 305, thedriving member 298 is laterally shifted within a driving sleeve 308.

I provide a rotary tapered valve m which is mounted within a companionbushing 3l2. This valve is adapted, upon rotation, to control the flowof fluid toward and away from the piston chambers 300. Thus fluidintroduced from the pipe line 234 enters a chamber 3, and from thischamber is directed through a central passage 3! 6, which communicateswith a peripheral valve port 3l8. This valve port 3l8 successivelyregisters or communicates with radial ports *3l9 in the bushing 3 l 2,which connect with passages 32!! provided in the support 290. Thisperipheral valve port 3 I 8 is timed so as to communicate with thepiston chambers 303 during the intake stroke of their companion pistons292, while a similar peripheral valve port 322 is timed to communicatewith those piston chambers 390 which are companion to the pistonsexperiencing their outer or compression stroke. Thus fluid underpressure is directed from the passages 320 through a peripheral passage324 in the bushing 3l2, and this passage, in turn, communicates with aradial port 326. Fluid under pressure from these ports 326 is directedthrough the peripheral valve port 322 and into a passage 328, whichcommunicates with an annular valve passage 330. It should be noted thatthis annular passage 330 is slightly enlarged at the point designated bythe numeral 332 (Figure 5),

, and fluid from this annular passage passes outwardly through the pipeline 230 into the rear extremity of the hydraulic actuator I24.Likewise, fluid under pressure in the pump 56 passes outwardly throughthe pipe line 232 to the right end of the hydraulic actuator H4 andthelower end of the actuator 96.

By having the low and high pressure peripheral ports arranged in themanner described above, I am able to positively preclude the. valve fromexperiencing any distortion which might otherwise result from thesubjection of the valve to these pressures. pressure experienced by thevalve in the peripheral port 322 is counteracted or neutralized by thefluid pressure acting within the annular passage 330 adjacent itsenlarged ortion 332. That is to say, any tendency of the fluid pressureacting on one side of the valve to cause said valve to bind or becomedistorted, is prevented by the neutralization of pressures on oppositesides of the valve. This neutralization or balancing of the valve isparticularly important when the fluid pressure reaches a substantialamount, as, for example, pressures in excess of flve hundred pounds persquare inch. It should be understood that it is very important to havethe tapered valve freely rotatable so as to prevent. wear and tomaintain a very close, accurate running flt.

It should also be noted that toward the larger end of the valve 310, thepressures acting thereon neutralize one another. Thus, for example, thehigh pressure fluid within the upper three radial ports 3l9 shown inFigure 6 act downwardly upon the valve, while the pressure in the twolower radial ports 3|9 and the peripheral port 3l8 act upwardly, therebyefiecting a substantially balanced condition. Attention is also directedto. the fact that by having the low pressure peripheral port 3l9 spacedaxially from the high pressure peripheral port 322 andthe communicatingannular port 330, the possibility of slippage of fluidbetween highpressure and low pressure ports is prevented. It will be seen in Figure8 that the upper three radial passages or ports 326, as well as theperipheral port 322, contain high pressure fluid, while the two lowerradial ports 326 contain low pressure fluid. There is suflicientpressure peripheral ports in the manner described,

I am able to reduce to a minimum the possibility of fluid slippagebetween high and low pressure valve ports. Obviously the reduction ofslippage is an extremely important factor in connection with pumpingdevices of the type disclosed here-" in, because, in the first place,fluid slippage causes serious increases in fluid temperatures, and, inthe second place, results in a decided decrease in 'mechanical andpropelling efliciency. Furthermore, pu ps such as the pumps 56 and 58,are employed in closed circuits which are so arranged that the fluiddischarged by the pump acts against one side--of an actuator piston andthe fluid displaced-by the advancing side of the actuator pis-, ton isthe sole charging medium introduced within the intake side of the pump.Hence, any slippage offluid, within the system would tend to seriouslyaffect the propelling effectiveness or emciency of the pump.

It will be seen that the high Attention is 'now directed to a pair ofgrooves 334 and 336 provided at the larger end. of the tapered valve am.The groove 334 communicates with the central valve passage M6 and assuch serves to return fluid which might slowly work its way along thesurface of the valve to the left, Figure 5, back to the central passage3| 6. It should be understood that the tapered construction of the valveis such as to provide a fluid seal within the closed circuit describedabove, and positively prevents the leakage or slippage of fluidlongitudinally of the valve toward its larger end to an extent thatwould impair the emcient functioning of the closed circuit.

To insure proper lubrication of the valve su face extending to the leftof the groove 334, Figure 5, I provide the groove 336. This groove 336is continuously connected through a conduit or pipe line 336 with apassage or port 340 of the distributor mechanism 200, Figures 14 and 15.A similar pipe line or conduit 338 communicates with the rotary valve inthe pump 56.. A portion of the fluid under pressure from the gear pump68 is directed through the pipe line or conduit 338 and thereby providea predetermined amount of fluid pressure within the groove 386. Under'normal operating conditions the pressure of the fluid within the groove336 exceeds the pressure of the fluid in the groove 334, therebypreventing the flow of fluid from the groove 334 to the left, butproviding a fluid film along the surface of the valve positioned to theleft of the groove 334, Figure 5. In other words, any tendency for aslight migration of fluid along this surface would be from the groove336 toward the groove 334. Thus it will be apparent that one of .theprimary functions of the groove 336, is to present a fluid body underincreased pressure at the point where the fluid from the groove 334might not in some instances provide the required amount of lubricationalong, the surface of the rotary valve at its larger end.

It should also be understood that the groove 336 provides a compensatingmeans to take care of fluctuations or variations in fluid pressurewithin the hydraulic system of control. Thus, for example, if thepressure of fluid within the low pressure side of the system is suddenlyincreased above the pressure of the fluid within the groove 336. saidgroove will permit a'compensating flow or migration of fluid from thegroove 334 into the groove 336. Such a sudden increase in fluid pressurewithin the low pressure side of the system takes place when the maincontrol valves l'l4'and I16 are suddenly shifted from rapid traverse tofeed. That is to say, certain of the valve ports within the main controlvalve llil are suddenly restricted so as to effect a momentary buildinup of fluid pressure within the low' pressure circuit, and in thisinstance the groove 336 provides a rel ef or compensating means.Furthermore. the expansion and contraction of the fluid are similarlycompensated for by the groove 336.

At this point it should be understood that my particular rotary 'valveconstruction with its compensating grooves has a very practicalapplication when used in connection with various types of apparatusother than lathes. Forex'ample, a valve of this type used in connectionwith a milling machine in which .climbing milling? is performed has avery practical application.

By elimbing milling, I mean the milling of a worksjpiece bymoving thework piece in the same'direction as the rotation of the milling cutteras distinguished from moving a work piece against the rotation of thecutter. In such instances a pressure may be built up on the advancingside of the actuator piston which is in excess of the pressure on thetrailing side as compared with the opposite conditions which exist inthe actuator pistons when used in the machine described in the presentapplication. The compensating groove 336 of the valve in such instancesprovides a very practical and eflicient operable means for bringingabout an automatic or self-adjustment of fluid conditions within thehigh and low pressure side of the circuits, and, in addition, performsits function of insuring proper lubrication of the valve at its largerend. In fact, my improved valve constructionequipped with the particulararrangement of the peripheral valve ports and the peripheral groovesdescribed above presents a very positive fluid seal within a closedcircuit, and at the same time insures longevity of the valve and itsbearing. when it is appreciated that pumps connected with machines suchas automatic lathes,

' milling machines, boring machines, and the like,

are subjected to substantially continuous operation day in and day out,the problem of insuring a true running fit of the tapered valve over anwithin the casing 342 and the shifting of this plug serves to vary thepressure conditions in accordance with the pressure which is requiredwithin the groove 336. Obviously the pressure within the groove 336 isnormally above the pressure of the fluid which passes from the gear pump68 through the pipe line 202 into the main control valve H0.

The distributor mechanism 200' serves 'as means for establishingtwo-pressure conditions from a single source. The single source ofsupply is the gear pump 68, and from this source fluid under differentpressures is employed, fluid under one pressure passing through the pipeline 202 and fluid under a higher pressure passing through the conduit338 to the compensating groove 336. By setting up a counter-pressure 'inthe groove 336, fluid is maintained within the circuit and thiscounter-pressure is greater than the normal low pressure fluid whichis'deliveredefor actuation purposes to the'hydraulic actuators.

In order to automatically take up any slight wear in the valve 3 I0, Ihave inserted a co'mpensa- (tor of conventional design indicatedgenerally conventional compensator. It will suffice to say that itincludes a pair of adjacently positioned rings 350 and 352, said ringsbeing provided with cooperating 'cam surfaces and a locking pin or key354. 'These rings automatically expand as a result of means providedwithin the device for effecting relative rotation between the rings,

and when the separation becomes great enough to clear the locking pin orkey 354, relative rotation of the rings will occur so asto take up anyslight wear in the valve. This device is designed to take up less than.0005', axial adjustment. It will be seen that this compensator 348 isinserted between the valve bushing 3l2 and an anti-friction bearing 356which is clamped by means of a collar 358 mounted upon the threadedsplit end of the valve member 3I8. Obviously other forms of compensatordevicesfor automatically taking up wear may be employed in combinationwith rotary valves without departing fromthe spirit and scope of myinvention.

In order to preclude the introduction of air within the fluid body ofthe hydraulic system, I have arranged the reservoir 52 in such a manneras to enable the calm or undisturbed entrance of fluid within saidreservoir. It will be apparent from Figure 2 that the reservoir 52.includes an outer casing formed by the frame or bed 42 and an innercasing 362. Fluid which is returned to the reservoir through a pipe line364, which connects the reservoir with the valve chamber 250, Figure 3,passes through a fixed, restricted ori- ,flce 366, Figure 2. It will beseen that this orifice is bell-mouthed on its entrance side and tapersto a larger opening on its egress side. Fluid passes from this orificethrough an inclined conduit 368 and is directed against a substantiallyconical surface 318, which has its apex at 312. This apex 312 ispositioned adjacent the mouth of the inclined conduit 368, and fluidfrom the conduit flows gently along the conical surface 310, whichblends into the side walls of the inner reservoir, thereby preventingthe fluid from being churned or swirled to such an extent as to de--velop air pockets or bubbles. In this manner the sudden ingress of thefluid is interrupted so as to preclude the agitation or stirring of thefluid body. In other words, a very calm undisturbed entrance of thefluid within the inner casing 362 takes place as a result of thestructural arrangement just described. Fluid from the inner tank 362overflows into the casing or tank 52. The slow overflow of fluid alsocontributes toward maintaining the fluid body which is withdrawn fromthe outer casing, free from air bubbles. To

- maintain a hydraulic circuit free from air bub- .within the circuit.

bles or pockets is of extreme importance, particularly in connectionwith hydraulic systems which are employed for moving machine tools andthe like. A very small amount of air within a circuit is sufficient toseriously impair the operating efliciency thereof. It should beunderstood that by employing myhydraulic system of control, I am able togovern the shifting of the tool carriages within a fraction of athousandth of an inch, and to accomplish this I have not only arrangedthe hydraulic actuators, pumps, and connecting conduits in such a manneras to provide a closed circuit, but have provided means for positivelypreventing the introduction of air Devices with which I am familiar havebeen employed heretofore to remove air from the system, but my improvedarrangement must be differentiated therefrom inasmuch as I propose toprevent the air from initially entering the system, thereby avoiding thenecessity of removing air from within the conduits forming a part of thehydraulic system of control. The mechanism just describedfor prevventing air from entering the hydraulic system is similar in somerespects to the system set forth in my Patent No. 1,985,748 whereinIhave disclosed a modified reservoir structure for effecting the calmentrance of fluid. Experience has shown that the inclusion of air withina hydraulic system not only causes pulsating effects resulting from thepresence of air pockets, but also causes the fluid to disintegrate. Thisis particularly true when air is trapped within a fluid, such as oil.

It will be noted that. the actuator piston H8 is provided with a pistonrod I28, on each side thereof, whereas the actuator piston I28 isprovided with a piston rod on only one side thereof. Obviously thevolume of fluid displaced from the advancing side of the piston H8 willbe equal to the volume of fluid received on the opposite side of thepiston, whereas the volume of fluid discharged from the advancing sideof the piston I28, as it moves forwardly, will be slightly greater thanthe volume taken in on the opposite side of the piston due to thepresence of the piston rod. To take care of this slight volumetricdifference, I provide a vent 269, Fig. 3, which is in continuouscommunication with'the conduit or pipe line 268. This vent is similar infunctional characteristics to the vents disclosed in one of my copendingapplications, Serial No. 439,306, filed March 27, 1930, and a detailedexplanation thereof in the present application is not necessary to aclear understanding of the invention. It will suffice to say, however,when a piston is equipped with a piston rod on either side thereof, asshown in the hydraulic actuator I I4, a vent, such as the vent 268, isnot needed. Both forms of pistons are disclosed in the presentapplication to show that my invention is not limited to any particularform of actuator construction, but is capable of employing pistonsequipped with rods on one or both sides thereof. In this connectionattention is again directed to the improved fluid compensatingarrangement, with which the rotary valve 3l0- is equipped. By having thegrooves 334 and 338 in the valve, a unique sealing of the fluid isobtained, and by this arrangement any change in fluid volume, due toincreased heat, et cetera, is compensated for, and the presence of fluidbetween the grooves positively prevents any fluid from leaving thesystem' when said system is functioning under-normal conditions.Attention is also directed to the fact that capillary action along thesurface between the grooves 334 and 336 contributes to the sealingeffectiveness of the rotary valve.

By causing the returned fluid to be directed against the conical surface318 withinthe fluid reservoir and then permitting the fluid from theinner reservoir to slowly overflow into the outer reservoir, I am ableto positively prevent air from pumps, driving means, etc., as a completeunit. 70

The spindle is not only supported by the unitary frame structure of thehead stockbut is so positione'd with respect to the fluid containedwithin the frame, such as the fluid within the reservoir,

that heat developed from the rotation of the spindle within its bearingsis appreciably dissipated through the contained fluid. Attention is alsodirected to the fact that the distributor mechanism 200 provides meanswhereby two pressure conditions from a single source of supply areobtained; Thatis to say, the mechanism 280 enables fluid delivered bythe gear pump to be directed through one conduit at one pressure andthrough another conduit at another pressure. This is extremely practicalin its application to various hydraulic systems of control wherein anauxiliary supplyof fluid at a pressure difiering frOm the dischargepressure of the pump is required. By using the mechanism 200, I precludethe necessity of using a second or auxiliary pump.

The foregoing statements regarding the functioning of my improved lathestructure have been substantiated by actual work in the field. Machinesconstructed in accordance with the teachings of my invention have beensubjected to severe actual working conditions in the shop and havematerially-increased shop production.

Obviously numerous changes and modifications may be made in certain ofthe structural features described above without departing from thespirit and scope of my invention, said invention being limited only bythe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters their intake stroke, said peripheral ports beingspacedaxially along the surface of said valve, and means. for automaticallymaintaining said valve in proper position of adjustment to insure thecircuit against fluid leakage.

2. In a hydraulic actuator system, a hydraulic circuit including ahydraulic actuator, a plunger pump adapted to deliver fluid to saidactuator, said pump having a support and a plurality of reciprocableplungers therein for subjecting fluid to pressure, a rotary taperedvalve in said pump for controlling the flow of fluid toward and awayfrom said plungers, a peripheral port in said valve adapted tosuccessively communicate with the pistons experiencing their compressingstroke, a peripheral port in said valve for successively communicatingwith the pistons experiencing their intake stroke, said peripheral portsbeing spaced axially along the surface of said valve, passageways insaid valve communicating with said ports whereby to neutralize the fluidpressures acting on the sides of the valve to thereby maintain the freeand accurate running fit of said valve, and means for automaticallymaintaining said valve .in proper position of adjustment to insure thecircuit against fluidleakalge.

3. In a hydraulic actuator system, a h'ydraulic circuit including ahydraulic actuator, a plunger pump adapted to deliver fluid to saidactuator,

said pump having a support and a plurality of reciprocable plungersthereinfor subjecting fluid to pressure, a rotary tapered valve" in saidpump for controlling the flow of fluid toward and away from saidplungers, a peripheral port in said valve adapted to successivelycommunicate with the pistons experiencing their compressing stroke, aperipheral port in said valve for successively communicating with thepistons experiencing their intake stroke, a-peripheral groove in saidvalve continuously in communication with the low pressure side thereof,a second groove spaced from the first groove and adapted forcommunication with an external source of fluid supply, and means forautomatically maintaining said valve in proper position of adjustment toinsure the circuit against fluid leakage.,

4. In a hydraulic actuator system, a hydraulic circuit including ahydraulic actuator, a plunger pump adapted to deliver fluid to saidactuator,

said pump having a' support and a pluralityof reciprocable plungerstherein for subjecting fluid to pressure, a rotary tapered valve in saidpump for controlling the flow of fluid toward and away from saidplungers, a peripheral port in said valve adapted to successivelycommunicate with the pistons experiencing their intake stroke, aperipheral groove in said valve continuously in communication with thelow pressure side thereof, a second groove spaced from the first grooveand adapted for communication with an external source of fluid supply,and means for maintain- !ng fluid pressure within said second mentionedperipheral groove which is in excess of the nor-' .mal low pressurefluid within the other groove, and means for automatically maintainingsaid valve in'proper position of adjustment to insure the circuitagainst fluid leakage.

5. In a hydraulic actuator system, a hydraulic circuit including ahydraulic actuator having a piston shiftable within a cylinder forpropelling a machine element or the like, a pump for supplying fluid tosaid actuator, said pump includ-- ing a plurality of reciprocablepistons, a rotary valve for controlling the flow of fluid toward andaway from said pistons, means associated with the valveto compensatefor'variation in fluid pressures acting upon said valve, and means toautomatically compensate for wear experienced by said valve duringrotation whereby to insure the circuit against fluid leakage.

6. A hydraulic actuator system including a fluid pump and a valvemechanism for controlling fluid delivered by said pump, a fluidreservoir 'for receiving fluid discharged by the pump,

said reservoir including inner and outer fluid containers and having acurved surface positioned at the point where the fluid initially entersthe inner container, whereby to counteract any tendvoir to said fluidpump.

'7. A hydraulic actuator system including a fluid pump and a valvemechanism for controlling fluid delivered to said pump, .a'fluidreservoir for receiving fluid discharged by the pump,

said reservoir including inner and outer fluid containers and having acurved surface terminating in an apex and positioned at the point" wherethe fluid enters the inner container, whereby to counteract any tendencyto agitate the fluid body and thereby preventthe introduction rapidtraverse pump for imparting rapid movement to said actuator, a highpressure pump for imparting feeding movement to said actuator,

said latter pump including a supporthavlng a plurality of reciprocablepistons and a rotary valve for controlling the flow of fluid toward andaway from said pistons, and a distributor mechanism positioned at thedischarge side of said rapid traverse pump, said distributor mechanismincluding means for delivering a portion of the fluid discharged by saidpump to said actuator and the remaining portion to the peripheralsurface of the rotary valve in said high pressure 9. In a hydraulicactuator system, a hydraulic actuator including a piston within acylinder, a rapid traverse pump for imparting rapid movement to saidactuator, a high pressure pump for imparting feeding movement to saidactuator, said latter pump including 'a support having a plurality ofreciprocable pistons and a rotary valve for controlling the flow offluid toward and away from said pistons, said rotary valve having aperipheral groove, and a distributor-mechanism positioned-at thedischarge side of said rapid traverse pump, said distributor mechanismincluding means for delivering a portion-of the fluid discharged by saidpump to said actuator and the remaining portion to the peripheral grooveof the rotary valve in said high pressure Pump.

10. A valve mechanism for receiving fluid under one pressure anddispatching same under another pressure, including a bearing, a valvemember in said bearing, said valve member and bearing being relativelyrotatable, the complementary bearing surfaces thereof varying indiameter, a peripheral port in said valve member for timinglycontrolling the dispatchment of fluid under the one pressure,complementary fluid conducting means in said bearing member,

a peripheral port in'said valve for dispatching fluid under the otherpressure, and complementary fluid conducting means in said bearingmember, said peripheral ports on the valve member being spaced axiallyalong the surface thereof in a manner tobalance the pressures actingupon said valve member.

11. A valve mechanism for receiving fluid under one pressure anddispatching same under another pressure, including a bearing, a valvemember in said bearing, said valve member and bearing beingrelativelyrotatable, the compiementary bearing surface thereof varying indiameter, a peripheral port in said valve member for timinglycontrolling the dispatchmentof fluid under the one pressure,complementary fluid conducting means in said bearing member, aperipheralport in said valve for dispatching fluid under the otherpressure, complementary fluid conducting means in said bearing member,said peripheral ports on the valve member being spaced axially along thesurface thereof, and passageways in said valve communicating with saidports whereby to neutralize the pressures acting on the sides of thevalve to thereby maintain the free and accurate running fit of saidvalveand bearing.

12. A valve mechanism for receiving fluid under one pressure anddispatching same under another. pressure, including a bearing, a valvemember in said bearing, said valve member and bearing being relativelyrotatable; the complementary bearing surfaces thereof varying indiameter, a peripheral port in said valve member for timinglycontrolling the dispatchment of fluid under the one pressure,complementary fluid conducting means in said bearing member, aperipheral port in said valve for dispatching fluid under the otherpressure, complementary fluid conducting means in said bearing member,peripheral fluid receiving means in said valve continuously incommunication with the low pressure side thereof, and a secondperipheral fluid receiving means spaced from said first peripheral fluidreceiving means and adapted for communication with an external source offluid supply.

13. In a. hydraulic actuator system, a valve mechanism for receivingfluid under one pressure and dispatching same under another pressure,said valve mechanism including a bearing,

a valve member in said bearing, said valve member and bearing beingrelatively rotatable, the

complementary bearing surfaces thereof varying in diameter, a peripheralport in said valve mem-' her for timingly controlling the dispatchmentof fluid under the one pressure, complementary fluid conducting means insaid bearing member, a peripheral port in said valve for dispatchingfluid under the other pressure, complementary fluid conducting means insaid bearing member, peripheral fluid receiving means continuously incommunication with the low pressure side of said valve, a secondperipheral fluid receiving means spaced from the first peripheral fluidreceiving means and adapted for communication with an external source offluid supply, and means for maintaining fluid pressure within saidsecond mentioned peripheral fluid receiving means which is in excess ofthe normal fluid pressure within the first peripheral fluid receivingmeans.

14. In a hydraulic system, a hydraulic circuit including a plungersupport, a plurality of reciprocable plungers therein for subjectingfluid to pressure, a hydraulic actuator for receiving fluid from saidplungers, a valve mechanism including a bearing, a valve member in saidbearing, said valve member and bearing being relatively rotatable, thecomplementary bearingsurfaces thereof varying in diameter to counteractfluid slippage along said surfaces, a peripheral port in said valveadapted to successively communicate with said plungers during theircompression stroke, and a peripheral port in said valve forsuccessively. communicating with said plungers during their intakestroke, said ports being axially spaced along the surface of said valvein a manher, to balance the pressures acting upon said valve member.

15. In a hydraulic system, a hydraulic circuit including a plungersupport, a plurality of reciprocable plungers therein for subjectingfluid to pressure, a hydraulic actuator for receiving fluid from saidplungers, a valve mechanism including a bearing, a valve member in saidbearing, said valve member and bearing being relatively rotatable, thecomplementary bearing surfaces thereof varying in diameter to counteractfluidslippage along said surfaces, a peripheral port in said valveadapted to successively communicate with said plungers during theircompression stroke, a peripheral port in said valve for successivelycommunicating with said plungers during their intake stroke, said portsbeing axially spaced along the surface of said valve, and

passageways communicating with said ports.

16. In ahydraulic system, a hydraulic circuit including a plungersupport, a plurality of reciprocable plungefs therein for subjectingfluid.

to pressure, a hydraulic actuator for receiving fluid from saidplungers, a valve mechanism including a bearin a valve member in saidbearing, said valve member an d bearing beingrelatively rotatable, thecomplementary bearing surfaces thereof varying in diameter to counteractfluid slippage along said surface, a peripheral port in said va veadapted to successively com- N municate with aid plungers during theircompression stroke, a peripheral port in said valve for successivelycommunicating with said plungers during their intake stroke, aperipheral fluid receiving means associated with said valve which iscontinuously in communication with the low pressure sidethereof,v and asecond peripheral fluid receiving means spaced from the first peripheralfluid receiving means and adapted for communication with an externalsource of fluid pp y.

17. In a hydraulic system, a hydraulic circuit including a plungersupport, a plurality of reciprocable plungers therein for'subjectingfluid to pressure, a hydraulic actuator for receiving fluid from saidplungers, a valve mechanism including a bearing, a valve member in saidbearing, said'valve member and bearing being relatively rotatable, thecomplementary bearing surfaces thereof varying in diameter to counteractfluid slippage along said surfaces, a peripheral port in said valveadapted to successively communicate with said plungers during theircompression stroke, a peripheral port in said valve for successivelycommunicating with said plungers during their intake stroke, aperipheral fluid receiving means associated with said valve which iscontinuously in communication with the low cation with an externalsource of fluid supply,

pressure side thereof, a second peripheral fluid receiving means spacedfrom the first p'eripheral fluid receiving means and adapted forcommuniand means for maintaining fluid pressure within said secondperipheral fluid receiving means which. is in excess of the normalpressure of the fluid within the -flrst peripheral fluid receivingmeans.

18. A valve mechanism for receiving fluid under one pressure anddispatching same under another pressure, including a bearing, a valvememher in said bearing, said valve member and hearing being relativelyrotatable, the complementary bearing surfaces thereof varying indiameter, a peripheral port in said valve member for timinglycontrolling the dijs'patchment of fluid under the one pressure,complementary fluid conducting means in said bearing member,'aperipheral port in said valve for dispatching fluid under the otherpressure, complementary fluid conducting means in said bearing member,and means for maintaining said valve and bearing in predeterminedcooperativerelation.

19. A valve mechanism for receiving fluid under one pressure anddispatching same under another pressure, including a bearing, a valvememher in said bearing, said valve member and bearing being relativelyrotatable, the complementary bearing surfaces thereof varying indiameter, a peripheral port in said valve member for timinglycontrolling the dispatchment of fluidunder the one pressure,complementary fluid conducting means in said bearing member, aperipheral port in said valve for dispatching fluid under the otherpressure, complementary fluid conducting means and thereby preventperiencing their compressing stroke and a peripheral port in said valveforsuccessively communicating with the pistons experiencing their intakestroke, said peripheral ports being spaced axially along the surface ofsaid valve in a manner to balance the fluid pressure acting upon saidvalve.

21. A plunger pump construction including a support having a pluralityof reciprocable plungers therein for subjecting fluid to pressure, arotary tapered vaive'in said pump for controlling the flow of fluidtoward and away from said plungers, a peripheral port in said valveadapted to successively communicate with the-pistons exper'iencing theircompressing stroke and a peripheral port in said valve for successivelycommunicating with the pistons experiencing-their intake stroke, saidperipheral ports being spaced axially along the surface of said valve,and passageways in said valve communicating withsaid ports ,whereby toneutralize the fluid pressures acting on the sides of the valve tothereby maintain the free and accurate running fit of said 22.'A plungerpump construction including'a support having a plurality of reciprocableplungers therein for subjecting fluid to pressure,

a rotary tapered valve in said pump for con-- trolling the flow of fluidtoward and away from said plungers, a peripheral port in said valveadapted to successively communicate with the pistons experiencing theircompressing stroke and a peripheral port in said valve for successivelycommunicating with the pistons experiencing their intake stroke, aperipheral groove insaid valve continuously in communication-with thelow pressure side thereof,and a second groove spaced from'the firstgroove and adapted 'for' communication with an external source of fluidpply- 23. A fluid reservoir structure including an outer fluidcontainer, a fluid container within said.first container, and means forconductingfluid into said inner container, said inner con-- tainerhaving a curved surface positioned at the point where the fluidinitially enters whereby to counteract any tendency to agitate the fluidbody r the introduction of air within said body. o

24. A fluid, reservoir structure including an outer fluid container,- 9.fluid container .within said first container, and means for conducting'fluid into said inner containen'saidinner container having a curvedsurfaceterminatingin an: apex and positioned at the point wherethefluidenters 'wherebyto counteract anytendency to agitate the fluidbody and thereby prevent the introduction of air within said .body'. t

25. .A fluid reservoir structure including an outer fluid container, afluid container within said first container, and means inclined with,

respect to the'vertical for conductin fluid into,

said inner container, said inner container having a curved surfacepositioned at'the point where the fluid enters whereby, counteract any,

tendency to agitate the fluid body and thereby prevent the introductionof air within said body. 26. A hydraulic unit structure including aunitary frame structure, a rotary supporting 5 member carried by saidunitary frame, a fluid pump associated with said frame, driving meansfor said pump carried by the frame, and a fluid reservoir within saidframe, portions of said frame providing wall portions of said reservoir,the fluid within said frame being so positioned with respect tosaid'rotary supporting member as to facilitate in dissipating heatresulting from rotation of said supporting member within said frame.

27. A hydraulic unit structure including a unitary frame structure,arotary supporting member carried by said-unitary frame, a fluid pumpassociated with said frame, driving means for said pump carried by theframe, a fluid 20 reservoir within said frame, portions of said frameproviding wall portions of said reservoir,

the fluidwithin said frame being so positioned with respect to saidrotary supporting member as to facilitate in dissipating heat resultingfrom rotation of said supporting member within said frame, and fluidretarding means within said reservoir.

28. A hydraulic unit structure including a v unitary frame structure, abearing withinsaid frame, arotary supporting spindle carried by saidbearing in said unitary frame, a fluid pump associated with said frame,driving means for said pump carried by the frame,- driving means forsaid spindle carried by said frame, and a a fluid reservoir within saidframe, @portions of said frame providing wall portions of saidraservoir, the fluid within said frame being so positioned with respectto said rotary supporting member as to facilitate in dissipating heatrea sulting from rotation of said supporting member within said frame.

29. In a hydraulic actuator system, a hydraulic circuit including ahydraulic actuator, and a plunger pump adapted to deliver fluid to saidactuator, said pump including a support having a plurality ofreciprocable plungers therein for subjecting fluid to pressure, a rotarytapered valve in said pump for controlling the flow of fluid toward andaway from said plungers, a peripheral port in said valve adapted tosuccessively communicate with the pistons experiencing their compressingstroke, a peripheral port in said valve for successively communicatingwith the piston experiencing their intake stroke, said peripheral portsbeing spaced axially along the surface of said valve, and means forautomatically maintaining said valve in proper position of adjustment toinsure the circuit against fluid leakage.

0 30. In a hydraulic actuator system, a hydraulic actuator, and aplunger pump adapted toudeliver fluid to said actuator, said pumpincluding a support having a plurality of reciprocable plungers thereinfor subjecting fluid to pressure,

5 a rotary tapered valve in said pump for controlling the flow of fluidtoward and away from said plungers,- a peripheral port in said valveadapted to successively communicate with the pistonsexperiencing theircompressing stroke, a

705' peripheral port in said valve for sucessively communicating withthe-pistons experiencing their intake stroke, said peripheral portsbeing placed axially along the surface of said valve, and passageways insaid valve communicating withsaid- 75v ports whereby to neutralize thefluid pressures acting on the sides of the valve to thereby maintain thefree and accurate running fit of said valve.

31. In a hydraulic actuator system, a hydraulic actuator,- a plungerpump adapted to deliver 5 fluid to said actuator, said pump' including asupport having a plurality of reciprocable plungers therein forsubjecting fluid to pressure, a rotary tapered valve in said pump forcontrolling the flowof fluid toward and away from said 10 plungers, aperipheral port in said valve adapted tosuccessively communicate withthe pistons experiencing their intake stroke, a peripheral groove insaid valve continuously in communication with the low pressure sidethereof, a second 15 groove spaced fromthe first groove and adapted forcommunication with an' external source of fluid supply, and meansfor-maintaining fluid pressure within said second mentioned peripheralgroove which is in excess of the normal low pres- 20 sure fluid withinthe other groove.

32. In a hydraulic actuator system a hydraulic actuator, a plunger pumpadapted to deliver fluid to said actuator, said pump having a pluralityof plungers valve means for controlling 35 the dispatchment of fluid toand from the plungers of said pump, and means for supplying fluidpressure to counteract the fluid pressure experienced by said valve indispatching fluid to and from said plungers, said counter-pressure serv-30 ing to preclude the leakage of fluid from said valve means. 33. In ahydraulic actuator system, a hydraulic actuator, high pressure pumpmeans for delivering fluid to said actuator, low pressure pump 35 meansfor delivering fluid to said actuator, valve means for controlling thetimed functioning of said pump means whereby to enable the first pumpwhen operating to be connected in a high pressure circuit and to enablethe second pump 4 y when operating to be connected in a low pressurecircuit, and means for developing a counterpressure which is greaterthan the pressure of the fluid in the low pressure circuit whereby tocounteract the leakage of fluid from one of said 5 circuits.

34. In a hydraulic actuator system, a hydraulic actuator, a singlesource of fluid pressure supply, means for conducting fluid from saidsource of supply to said actuator, means for conducting 5o fluid fromsaid source of supply to a point externally of said actuator, and meansfor causing the fluid from said single source to be delivered at onepressure to said actuator and at another pressure to the pointpositioned externally of said 5 actuator.

35. In a hydraulic actuator system, a hydraulic actuator, a singlesource of' fluid pressure supply, means for conducting fluid from saidsource of supply to said actuator, means for conducting o fluid fromsaid source of supply to a point externally of said actuator, andadjustable means for causing fluid from said single source to bedelivered at one pressure to said actuator and at another pressure tothe point positioned exter- 5 nally of said actuator.

36. In a fluid power system, a fluid actuator including a cylinder andpiston construction, a fluid circuit operatively associated with saidhydraulic actuator, a. fluid pressure generating mechanism in said fluidcircuit for producing a fluid flow 'under pressure to operate saidactuator, said crating mechanism for automatically adjusting andmaintaining said flow'controi means free from fluid leakage.

37. In a fluid power system, a fluid actuator am, said mechanismincluding rotary and axially adjustable means for timingly controllingthe" flo'w of fluid to and from said mechanism, and means within saidfluid pressure generating mechanism for automatically adjusting an'dmaintaining said flew control free from fluid leakage.

ERNEST J. SVENSON.

